src/api.h

   1 // Copyright 2012 the V8 project authors. All rights reserved.
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  27
  28 #ifndef V8_API_H_
  29 #define V8_API_H_
  30
  31 #include "v8.h"
  32
  33 #include "../include/v8-testing.h"
  34 #include "contexts.h"
  35 #include "factory.h"
  36 #include "isolate.h"
  37 #include "list-inl.h"
  38
  39 namespace v8 {
  40
  41 // Constants used in the implementation of the API.  The most natural thing
  42 // would usually be to place these with the classes that use them, but
  43 // we want to keep them out of v8.h because it is an externally
  44 // visible file.
  45 class Consts {
  46  public:
  47   enum TemplateType {
  48     FUNCTION_TEMPLATE = 0,
  49     OBJECT_TEMPLATE = 1
  50   };
  51 };
  52
  53
  54 // Utilities for working with neander-objects, primitive
  55 // env-independent JSObjects used by the api.
  56 class NeanderObject {
  57  public:
  58   explicit NeanderObject(v8::internal::Isolate* isolate, int size);
  59   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
  60   explicit inline NeanderObject(v8::internal::Object* obj);
  61   inline v8::internal::Object* get(int index);
  62   inline void set(int index, v8::internal::Object* value);
  63   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
  64   int size();
  65  private:
  66   v8::internal::Handle<v8::internal::JSObject> value_;
  67 };
  68
  69
  70 // Utilities for working with neander-arrays, a simple extensible
  71 // array abstraction built on neander-objects.
  72 class NeanderArray {
  73  public:
  74   explicit NeanderArray(v8::internal::Isolate* isolate);
  75   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
  76   inline v8::internal::Handle<v8::internal::JSObject> value() {
  77     return obj_.value();
  78   }
  79
  80   void add(v8::internal::Handle<v8::internal::Object> value);
  81
  82   int length();
  83
  84   v8::internal::Object* get(int index);
  85   // Change the value at an index to undefined value. If the index is
  86   // out of bounds, the request is ignored. Returns the old value.
  87   void set(int index, v8::internal::Object* value);
  88  private:
  89   NeanderObject obj_;
  90 };
  91
  92
  93 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
  94     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
  95
  96
  97 NeanderObject::NeanderObject(v8::internal::Object* obj)
  98     : value_(v8::internal::Handle<v8::internal::JSObject>(
  99         v8::internal::JSObject::cast(obj))) { }
 100
 101
 102 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
 103     : obj_(obj) { }
 104
 105
 106 v8::internal::Object* NeanderObject::get(int offset) {
 107   ASSERT(value()->HasFastObjectElements());
 108   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
 109 }
 110
 111
 112 void NeanderObject::set(int offset, v8::internal::Object* value) {
 113   ASSERT(value_->HasFastObjectElements());
 114   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
 115 }
 116
 117
 118 template <typename T> inline T ToCData(v8::internal::Object* obj) {
 119   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 120   return reinterpret_cast<T>(
 121       reinterpret_cast<intptr_t>(
 122           v8::internal::Foreign::cast(obj)->foreign_address()));
 123 }
 124
 125
 126 template <typename T>
 127 inline v8::internal::Handle<v8::internal::Object> FromCData(
 128     v8::internal::Isolate* isolate, T obj) {
 129   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 130   return isolate->factory()->NewForeign(
 131       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 132 }
 133
 134
 135 class ApiFunction {
 136  public:
 137   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 138   v8::internal::Address address() { return addr_; }
 139  private:
 140   v8::internal::Address addr_;
 141 };
 142
 143
 144
 145 class RegisteredExtension {
 146  public:
 147   explicit RegisteredExtension(Extension* extension);
 148   static void Register(RegisteredExtension* that);
 149   static void UnregisterAll();
 150   Extension* extension() { return extension_; }
 151   RegisteredExtension* next() { return next_; }
 152   static RegisteredExtension* first_extension() { return first_extension_; }
 153  private:
 154   Extension* extension_;
 155   RegisteredExtension* next_;
 156   static RegisteredExtension* first_extension_;
 157 };
 158
 159
 160 #define OPEN_HANDLE_LIST(V)                    \
 161   V(Template, TemplateInfo)                    \
 162   V(FunctionTemplate, FunctionTemplateInfo)    \
 163   V(ObjectTemplate, ObjectTemplateInfo)        \
 164   V(Signature, SignatureInfo)                  \
 165   V(AccessorSignature, FunctionTemplateInfo)   \
 166   V(TypeSwitch, TypeSwitchInfo)                \
 167   V(Data, Object)                              \
 168   V(RegExp, JSRegExp)                          \
 169   V(Object, JSObject)                          \
 170   V(Array, JSArray)                            \
 171   V(ArrayBuffer, JSArrayBuffer)                \
 172   V(ArrayBufferView, JSArrayBufferView)        \
 173   V(TypedArray, JSTypedArray)                  \
 174   V(Uint8Array, JSTypedArray)                  \
 175   V(Uint8ClampedArray, JSTypedArray)           \
 176   V(Int8Array, JSTypedArray)                   \
 177   V(Uint16Array, JSTypedArray)                 \
 178   V(Int16Array, JSTypedArray)                  \
 179   V(Uint32Array, JSTypedArray)                 \
 180   V(Int32Array, JSTypedArray)                  \
 181   V(Float32Array, JSTypedArray)                \
 182   V(Float64Array, JSTypedArray)                \
 183   V(DataView, JSDataView)                      \
 184   V(String, String)                            \
 185   V(Symbol, Symbol)                            \
 186   V(Script, Object)                            \
 187   V(Function, JSFunction)                      \
 188   V(Message, JSObject)                         \
 189   V(Context, Context)                          \
 190   V(External, Foreign)                         \
 191   V(StackTrace, JSArray)                       \
 192   V(StackFrame, JSObject)                      \
 193   V(DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 194
 195
 196 class Utils {
 197  public:
 198   static inline bool ApiCheck(bool condition,
 199                               const char* location,
 200                               const char* message) {
 201     if (!condition) Utils::ReportApiFailure(location, message);
 202     return condition;
 203   }
 204
 205   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 206   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 207
 208   static inline Local<Context> ToLocal(
 209       v8::internal::Handle<v8::internal::Context> obj);
 210   static inline Local<Value> ToLocal(
 211       v8::internal::Handle<v8::internal::Object> obj);
 212   static inline Local<Function> ToLocal(
 213       v8::internal::Handle<v8::internal::JSFunction> obj);
 214   static inline Local<String> ToLocal(
 215       v8::internal::Handle<v8::internal::String> obj);
 216   static inline Local<Symbol> ToLocal(
 217       v8::internal::Handle<v8::internal::Symbol> obj);
 218   static inline Local<RegExp> ToLocal(
 219       v8::internal::Handle<v8::internal::JSRegExp> obj);
 220   static inline Local<Object> ToLocal(
 221       v8::internal::Handle<v8::internal::JSObject> obj);
 222   static inline Local<Array> ToLocal(
 223       v8::internal::Handle<v8::internal::JSArray> obj);
 224   static inline Local<ArrayBuffer> ToLocal(
 225       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 226   static inline Local<ArrayBufferView> ToLocal(
 227       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 228   static inline Local<DataView> ToLocal(
 229       v8::internal::Handle<v8::internal::JSDataView> obj);
 230
 231   static inline Local<TypedArray> ToLocal(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233   static inline Local<Uint8Array> ToLocalUint8Array(
 234       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 235   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 236       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 237   static inline Local<Int8Array> ToLocalInt8Array(
 238       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 239   static inline Local<Uint16Array> ToLocalUint16Array(
 240       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 241   static inline Local<Int16Array> ToLocalInt16Array(
 242       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 243   static inline Local<Uint32Array> ToLocalUint32Array(
 244       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 245   static inline Local<Int32Array> ToLocalInt32Array(
 246       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 247   static inline Local<Float32Array> ToLocalFloat32Array(
 248       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 249   static inline Local<Float64Array> ToLocalFloat64Array(
 250       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 251
 252   static inline Local<Message> MessageToLocal(
 253       v8::internal::Handle<v8::internal::Object> obj);
 254   static inline Local<StackTrace> StackTraceToLocal(
 255       v8::internal::Handle<v8::internal::JSArray> obj);
 256   static inline Local<StackFrame> StackFrameToLocal(
 257       v8::internal::Handle<v8::internal::JSObject> obj);
 258   static inline Local<Number> NumberToLocal(
 259       v8::internal::Handle<v8::internal::Object> obj);
 260   static inline Local<Integer> IntegerToLocal(
 261       v8::internal::Handle<v8::internal::Object> obj);
 262   static inline Local<Uint32> Uint32ToLocal(
 263       v8::internal::Handle<v8::internal::Object> obj);
 264   static inline Local<FunctionTemplate> ToLocal(
 265       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 266   static inline Local<ObjectTemplate> ToLocal(
 267       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 268   static inline Local<Signature> ToLocal(
 269       v8::internal::Handle<v8::internal::SignatureInfo> obj);
 270   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 271       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 272   static inline Local<TypeSwitch> ToLocal(
 273       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 274   static inline Local<External> ExternalToLocal(
 275       v8::internal::Handle<v8::internal::JSObject> obj);
 276   static inline Local<DeclaredAccessorDescriptor> ToLocal(
 277       v8::internal::Handle<v8::internal::DeclaredAccessorDescriptor> obj);
 278
 279 #define DECLARE_OPEN_HANDLE(From, To) \
 280   static inline v8::internal::Handle<v8::internal::To> \
 281       OpenHandle(const From* that, bool allow_empty_handle = false);
 282
 283 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 284
 285 #undef DECLARE_OPEN_HANDLE
 286
 287   template<class From, class To>
 288   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 289     ASSERT(obj.is_null() || !obj->IsTheHole());
 290     return Local<To>(reinterpret_cast<To*>(obj.location()));
 291   }
 292
 293   template <class T>
 294   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 295       const v8::Persistent<T>& persistent) {
 296     return v8::internal::Handle<v8::internal::Object>(
 297         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 298   }
 299
 300   template <class T>
 301   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 302       v8::Persistent<T>* persistent) {
 303     return OpenPersistent(*persistent);
 304   }
 305
 306   template <class From, class To>
 307   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 308     return OpenHandle(*handle);
 309   }
 310
 311  private:
 312   static void ReportApiFailure(const char* location, const char* message);
 313 };
 314
 315
 316 template <class T>
 317 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 318     v8::EscapableHandleScope* scope) {
 319   v8::internal::Handle<T> handle;
 320   if (!is_null()) {
 321     handle = *this;
 322   }
 323   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 324 }
 325
 326
 327 template <class T>
 328 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 329   return reinterpret_cast<T*>(obj.location());
 330 }
 331
 332 template <class T>
 333 inline v8::Local<T> ToApiHandle(
 334     v8::internal::Handle<v8::internal::Object> obj) {
 335   return Utils::Convert<v8::internal::Object, T>(obj);
 336 }
 337
 338
 339 // Implementations of ToLocal
 340
 341 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 342   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 343     return Convert<v8::internal::From, v8::To>(obj);  \
 344   }
 345
 346
 347 #define MAKE_TO_LOCAL_TYPED_ARRAY(TypedArray, typeConst)                    \
 348   Local<v8::TypedArray> Utils::ToLocal##TypedArray(                         \
 349       v8::internal::Handle<v8::internal::JSTypedArray> obj) {               \
 350     ASSERT(obj->type() == typeConst);                                       \
 351     return Convert<v8::internal::JSTypedArray, v8::TypedArray>(obj);        \
 352   }
 353
 354
 355 MAKE_TO_LOCAL(ToLocal, Context, Context)
 356 MAKE_TO_LOCAL(ToLocal, Object, Value)
 357 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 358 MAKE_TO_LOCAL(ToLocal, String, String)
 359 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 360 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 361 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 362 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 363 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 364 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 365 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 366 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 367
 368 MAKE_TO_LOCAL_TYPED_ARRAY(Uint8Array, kExternalUnsignedByteArray)
 369 MAKE_TO_LOCAL_TYPED_ARRAY(Uint8ClampedArray, kExternalPixelArray)
 370 MAKE_TO_LOCAL_TYPED_ARRAY(Int8Array, kExternalByteArray)
 371 MAKE_TO_LOCAL_TYPED_ARRAY(Uint16Array, kExternalUnsignedShortArray)
 372 MAKE_TO_LOCAL_TYPED_ARRAY(Int16Array, kExternalShortArray)
 373 MAKE_TO_LOCAL_TYPED_ARRAY(Uint32Array, kExternalUnsignedIntArray)
 374 MAKE_TO_LOCAL_TYPED_ARRAY(Int32Array, kExternalIntArray)
 375 MAKE_TO_LOCAL_TYPED_ARRAY(Float32Array, kExternalFloatArray)
 376 MAKE_TO_LOCAL_TYPED_ARRAY(Float64Array, kExternalDoubleArray)
 377
 378 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 379 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 380 MAKE_TO_LOCAL(ToLocal, SignatureInfo, Signature)
 381 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 382 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 383 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 384 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 385 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 386 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 387 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 388 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 389 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 390 MAKE_TO_LOCAL(ToLocal, DeclaredAccessorDescriptor, DeclaredAccessorDescriptor)
 391
 392 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 393 #undef MAKE_TO_LOCAL
 394
 395
 396 // Implementations of OpenHandle
 397
 398 #define MAKE_OPEN_HANDLE(From, To)                                          \
 399   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                 \
 400     const v8::From* that, bool allow_empty_handle) {                        \
 401     EXTRA_CHECK(allow_empty_handle || that != NULL);                        \
 402     EXTRA_CHECK(that == NULL ||                                             \
 403         !(*reinterpret_cast<v8::internal::To**>(                            \
 404             const_cast<v8::From*>(that)))->IsFailure());                    \
 405     return v8::internal::Handle<v8::internal::To>(                          \
 406         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that))); \
 407   }
 408
 409 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 410
 411 #undef MAKE_OPEN_HANDLE
 412 #undef OPEN_HANDLE_LIST
 413
 414
 415 namespace internal {
 416
 417 // Tracks string usage to help make better decisions when
 418 // externalizing strings.
 419 //
 420 // Implementation note: internally this class only tracks fresh
 421 // strings and keeps a single use counter for them.
 422 class StringTracker {
 423  public:
 424   // Records that the given string's characters were copied to some
 425   // external buffer. If this happens often we should honor
 426   // externalization requests for the string.
 427   void RecordWrite(Handle<String> string) {
 428     Address address = reinterpret_cast<Address>(*string);
 429     Address top = isolate_->heap()->NewSpaceTop();
 430     if (IsFreshString(address, top)) {
 431       IncrementUseCount(top);
 432     }
 433   }
 434
 435   // Estimates freshness and use frequency of the given string based
 436   // on how close it is to the new space top and the recorded usage
 437   // history.
 438   inline bool IsFreshUnusedString(Handle<String> string) {
 439     Address address = reinterpret_cast<Address>(*string);
 440     Address top = isolate_->heap()->NewSpaceTop();
 441     return IsFreshString(address, top) && IsUseCountLow(top);
 442   }
 443
 444  private:
 445   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 446
 447   static inline bool IsFreshString(Address string, Address top) {
 448     return top - kFreshnessLimit <= string && string <= top;
 449   }
 450
 451   inline bool IsUseCountLow(Address top) {
 452     if (last_top_ != top) return true;
 453     return use_count_ < kUseLimit;
 454   }
 455
 456   inline void IncrementUseCount(Address top) {
 457     if (last_top_ != top) {
 458       use_count_ = 0;
 459       last_top_ = top;
 460     }
 461     ++use_count_;
 462   }
 463
 464   // Single use counter shared by all fresh strings.
 465   int use_count_;
 466
 467   // Last new space top when the use count above was valid.
 468   Address last_top_;
 469
 470   Isolate* isolate_;
 471
 472   // How close to the new space top a fresh string has to be.
 473   static const int kFreshnessLimit = 1024;
 474
 475   // The number of uses required to consider a string useful.
 476   static const int kUseLimit = 32;
 477
 478   friend class Isolate;
 479
 480   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 481 };
 482
 483
 484 class DeferredHandles {
 485  public:
 486   ~DeferredHandles();
 487
 488  private:
 489   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 490       : next_(NULL),
 491         previous_(NULL),
 492         first_block_limit_(first_block_limit),
 493         isolate_(isolate) {
 494     isolate->LinkDeferredHandles(this);
 495   }
 496
 497   void Iterate(ObjectVisitor* v);
 498
 499   List<Object**> blocks_;
 500   DeferredHandles* next_;
 501   DeferredHandles* previous_;
 502   Object** first_block_limit_;
 503   Isolate* isolate_;
 504
 505   friend class HandleScopeImplementer;
 506   friend class Isolate;
 507 };
 508
 509
 510 // This class is here in order to be able to declare it a friend of
 511 // HandleScope.  Moving these methods to be members of HandleScope would be
 512 // neat in some ways, but it would expose internal implementation details in
 513 // our public header file, which is undesirable.
 514 //
 515 // An isolate has a single instance of this class to hold the current thread's
 516 // data. In multithreaded V8 programs this data is copied in and out of storage
 517 // so that the currently executing thread always has its own copy of this
 518 // data.
 519 class HandleScopeImplementer {
 520  public:
 521   explicit HandleScopeImplementer(Isolate* isolate)
 522       : isolate_(isolate),
 523         blocks_(0),
 524         entered_contexts_(0),
 525         saved_contexts_(0),
 526         spare_(NULL),
 527         call_depth_(0),
 528         last_handle_before_deferred_block_(NULL) { }
 529
 530   ~HandleScopeImplementer() {
 531     DeleteArray(spare_);
 532   }
 533
 534   // Threading support for handle data.
 535   static int ArchiveSpacePerThread();
 536   char* RestoreThread(char* from);
 537   char* ArchiveThread(char* to);
 538   void FreeThreadResources();
 539
 540   // Garbage collection support.
 541   void Iterate(v8::internal::ObjectVisitor* v);
 542   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 543
 544
 545   inline internal::Object** GetSpareOrNewBlock();
 546   inline void DeleteExtensions(internal::Object** prev_limit);
 547
 548   inline void IncrementCallDepth() {call_depth_++;}
 549   inline void DecrementCallDepth() {call_depth_--;}
 550   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 551
 552   inline void EnterContext(Handle<Context> context);
 553   inline void LeaveContext();
 554   inline bool LastEnteredContextWas(Handle<Context> context);
 555
 556   // Returns the last entered context or an empty handle if no
 557   // contexts have been entered.
 558   inline Handle<Context> LastEnteredContext();
 559
 560   inline void SaveContext(Context* context);
 561   inline Context* RestoreContext();
 562   inline bool HasSavedContexts();
 563
 564   inline List<internal::Object**>* blocks() { return &blocks_; }
 565   Isolate* isolate() const { return isolate_; }
 566
 567   void ReturnBlock(Object** block) {
 568     ASSERT(block != NULL);
 569     if (spare_ != NULL) DeleteArray(spare_);
 570     spare_ = block;
 571   }
 572
 573  private:
 574   void ResetAfterArchive() {
 575     blocks_.Initialize(0);
 576     entered_contexts_.Initialize(0);
 577     saved_contexts_.Initialize(0);
 578     spare_ = NULL;
 579     last_handle_before_deferred_block_ = NULL;
 580     call_depth_ = 0;
 581   }
 582
 583   void Free() {
 584     ASSERT(blocks_.length() == 0);
 585     ASSERT(entered_contexts_.length() == 0);
 586     ASSERT(saved_contexts_.length() == 0);
 587     blocks_.Free();
 588     entered_contexts_.Free();
 589     saved_contexts_.Free();
 590     if (spare_ != NULL) {
 591       DeleteArray(spare_);
 592       spare_ = NULL;
 593     }
 594     ASSERT(call_depth_ == 0);
 595   }
 596
 597   void BeginDeferredScope();
 598   DeferredHandles* Detach(Object** prev_limit);
 599
 600   Isolate* isolate_;
 601   List<internal::Object**> blocks_;
 602   // Used as a stack to keep track of entered contexts.
 603   List<Context*> entered_contexts_;
 604   // Used as a stack to keep track of saved contexts.
 605   List<Context*> saved_contexts_;
 606   Object** spare_;
 607   int call_depth_;
 608   Object** last_handle_before_deferred_block_;
 609   // This is only used for threading support.
 610   HandleScopeData handle_scope_data_;
 611
 612   void IterateThis(ObjectVisitor* v);
 613   char* RestoreThreadHelper(char* from);
 614   char* ArchiveThreadHelper(char* to);
 615
 616   friend class DeferredHandles;
 617   friend class DeferredHandleScope;
 618
 619   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 620 };
 621
 622
 623 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 624
 625
 626 void HandleScopeImplementer::SaveContext(Context* context) {
 627   saved_contexts_.Add(context);
 628 }
 629
 630
 631 Context* HandleScopeImplementer::RestoreContext() {
 632   return saved_contexts_.RemoveLast();
 633 }
 634
 635
 636 bool HandleScopeImplementer::HasSavedContexts() {
 637   return !saved_contexts_.is_empty();
 638 }
 639
 640
 641 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 642   entered_contexts_.Add(*context);
 643 }
 644
 645
 646 void HandleScopeImplementer::LeaveContext() {
 647   entered_contexts_.RemoveLast();
 648 }
 649
 650
 651 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 652   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 653 }
 654
 655
 656 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 657   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 658   return Handle<Context>(entered_contexts_.last());
 659 }
 660
 661
 662 // If there's a spare block, use it for growing the current scope.
 663 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 664   internal::Object** block = (spare_ != NULL) ?
 665       spare_ :
 666       NewArray<internal::Object*>(kHandleBlockSize);
 667   spare_ = NULL;
 668   return block;
 669 }
 670
 671
 672 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 673   while (!blocks_.is_empty()) {
 674     internal::Object** block_start = blocks_.last();
 675     internal::Object** block_limit = block_start + kHandleBlockSize;
 676 #ifdef DEBUG
 677     // SealHandleScope may make the prev_limit to point inside the block.
 678     if (block_start <= prev_limit && prev_limit <= block_limit) {
 679 #ifdef ENABLE_HANDLE_ZAPPING
 680       internal::HandleScope::ZapRange(prev_limit, block_limit);
 681 #endif
 682       break;
 683     }
 684 #else
 685     if (prev_limit == block_limit) break;
 686 #endif
 687
 688     blocks_.RemoveLast();
 689 #ifdef ENABLE_HANDLE_ZAPPING
 690     internal::HandleScope::ZapRange(block_start, block_limit);
 691 #endif
 692     if (spare_ != NULL) {
 693       DeleteArray(spare_);
 694     }
 695     spare_ = block_start;
 696   }
 697   ASSERT((blocks_.is_empty() && prev_limit == NULL) ||
 698          (!blocks_.is_empty() && prev_limit != NULL));
 699 }
 700
 701
 702 // Interceptor functions called from generated inline caches to notify
 703 // CPU profiler that external callbacks are invoked.
 704 void InvokeAccessorGetterCallback(
 705     v8::Local<v8::String> property,
 706     const v8::PropertyCallbackInfo<v8::Value>& info,
 707     v8::AccessorGetterCallback getter);
 708
 709 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 710                             v8::FunctionCallback callback);
 711
 712 class Testing {
 713  public:
 714   static v8::Testing::StressType stress_type() { return stress_type_; }
 715   static void set_stress_type(v8::Testing::StressType stress_type) {
 716     stress_type_ = stress_type;
 717   }
 718
 719  private:
 720   static v8::Testing::StressType stress_type_;
 721 };
 722
 723 } }  // namespace v8::internal
 724
 725 #endif  // V8_API_H_